Grand Theft Auto IV, is a game about choice and perspective. "What does the American dream mean today," was printed on the back of the box and the game runs with the theme. Liberty City, like the city and country it was based on, is a land of dichotomies: Pessimism vs. Optimism, Principles vs. Greed, Promise vs. Reality. Each of these dichotomies reflect part of American life, and through the lens of an immigrant, they are given a different perceive than we normally receive in media.
While Niko's American dream may be different from another mans, their shared pursuit of dreams makes both Americans.